Family Pleromidae Sollas, 1888

Abstract

Pleromidae Sollas (Demospongiae, ‘lithistids’), including Pleromatidae Lendenfeld and Megamorina Zittel, contains two valid extant genera, with four species found in deep water, and known predominantly from the Pacific. These are polymorphic massive irregular to thick auricular and conical sponges. Fossil pleromids are reported with certainty from the Late Jurassic, with numerous representatives in the Late Cretaceous and also Jurassic. Desmas are arched megaclones, usually smooth. Other megascleres include large choanosomal and ectosomal oxeas, and ectosomal dichotriaenes and anatriaenes. Microscleres are spirasters or amphiasters, usually of two types, and microspined microxeas and/or styles. Genera are differentiated on the basis of presence or absence of anatriaenes and type of microscleres.